as for you taking the Mk5 wings. Yup, that will happen.. NOT! Tear an aircraft to pieces to take the wings and put it on your old clapped out piece of .....
It was being discussed as long ago as 2002 for the SF mini-fleet. In the end, I believe they paid Marshalls to rebuild the wings on some of them after their abuse in Op BLEED (horrible op name!) and follow-on Ops...
The other reasoning (at least for the SF mini-fleet) was the belief back then that helicopter refuelling was imminent with Mk3 Chinook - the J wings have the outboard hard points under the skin required for the pods.
The Mk5 is a bit of a conundrum - original procurement intentions notwithstanding, it's a short version of a "strat" lifter...since even the Mk4 isn't operating anywhere near it's ceiling limits, flying around w/one less pallet seems even sillier. So if you're going to "borrow" the wings off some, those would be the obvious choice...